Maybe an ABS/Brake Powers Assist issue? (1 Viewer)

[MH_Stevens]

2004 with 225K miles.
INTERMITTENT (meaning 50% of the time symptoms not evident) pedal and steering wheel vibration, biting on braking. Usually gentle breaking like as using brakes to slow when going down grade.
Feels the same as warped rotors but all rotors and pads and calipers are new. Sometimes it feels like the ABS is coming on and off.

OTHER CLUES
1) I've notice changes level changes in the brake fluid reservoir
2) I bleed the brakes and fluid would not flow from the drivers side rear line unless the engine was on to assist.

 

[2001LC]

With warped rotor (uneven deposits on disk) we see steering wheel vibrate during breaking once brakes hot (down hill brake use) It is a bad driving habit to use brakes to control speed on the down hill. Use transmission is second nature to me, in the Rockies. Half a day at Dealership and they'll turn rotor in place.

When light brake stop steering wheel vibration. Likely wheel bearings loose. Lift tire off ground and grab at 12 & 6. See if it rocks, yes not good. Place finger between caliper and wheel as you rock wheel, does it pinch finger. Likely wheel bearing not properly serviced (loose).

 

[MH_Stevens]

Thanks for reply but all brakes including rotors NEW and bearings serviced and good.
NOTE the problem is INTERMITTENT. In my experience the issues you suggest cause a permanent condition.

 

[OutoftheMud]

I had the same symptoms in an 03 4runner, same braking system so I'll post up...

On hard stops it felt like the rotors were warped, truck would pulse, but I didn't think it was ABS.
I replaced all rotors and pads, they were needed anyway, but the issue didn't go away. I bled the brakes and couldn't get any air to come out...
I finally downloaded Techstream and used the air bleed which activates the ABS solenoids when bleeding, the issue went away, truck stops better than it has in 3 years. Its like the ABS was being activated all the time or something, weird solution, but it fixed my problem.

 

[2001LC]

Thanks for reply but all brakes including rotors NEW and bearings serviced and good.
NOTE the problem is INTERMITTENT. In my experience the issues you suggest cause a permanent condition.

I always look to last work preformed first. Brakes new, (assume means pads) and rotor NEW and calipers is first place. Are they OEM or aftermarket or combination is also consideration.

It also import to bed the new pads to new disk/rotor. Then let cool without holding brake pedal held down while stopped, at all. You did bed then right?

The fluid level is set after evacuating accumulator. Read what Toyota spent extra $ to emboss on the reservoir. Overfilling of reservoir is common and a big no no done very often. Don't do it!

Once you complet topping.

Turn IG key to ON. Time how long booster motor runs as fluid draws down. Spec is 30 to 40 seconds.

If over 40 seconds likely leak, air in system or malfunction in that order after flushing.

Brake pedal can become mushy as fluid boils, which if moisture in fluid causes it to boils at lower temp. This is why we flush, to remove moisture. Air bleeding in system is secondary to the flushing/bleeding or working on brakes when line removed.

Your fluid not bleeding from DS rear without engine on is correct. Actually you do not need engine on. Only need IG key ON, and too press brake pedal for rears. To bleed the fronts you need IG key ON and to pump pedal (20 times at first, the 3 to 5) then press and hold. Always sung down bleeder before releasing pedal or air may suck in bleeder.

After bleeding drive on dirt road and stomp on brakes activating ABS three times. Then go bleed some more.

The video above was newer OEM pads with newer aftermarket rotor (~20K miles). The rotor showed rust staining from setting of pad imprint on them. The condition of steering wheel vib, did not reveal itself until a driver used brakes for down hill speed control. Doing so heated the brakes (rotors/disk and pads). Only then did steering wheel vibrate, not all the time! We learned the shop did not bed new pads and rotor. On vehicle turning of disk solved the issue. Driver learned to use transmission to control speed help insure brakes there when needed.

Try driving on the down hill and uses brakes very often to overheat, see what happens when they get very hot, warped rotors as they call it, shows themselves when hot more so then just coming to a stop when cool

I find bearings are rarely service properly. Try the both test I outlined with tire off the ground. Then let see what you report. To check sanp ring gap you must pull grease cap. But wide gap would not cause your issue.

Both of these are most common steering wheel vibration. There are other reason, but start here.

If ABS activating. It is loud and annoying. Crunch crunch crunch. Loose wheel bearing cause this usual on HWY turns. ABS activates as hub wobbles, the sensor reads as speed change.

A loose wheel speed sensor can act up also, and may set off a DTC. Or a cracked one, which set off a DTC (CEL or ABS light) usually

 

[MH_Stevens]

2001LC thanks for a great write up and giving such a work schedule. I do see my bleeding was, well bleeding awful and will do.
I will follow your work schedule and report back.

 

[2001LC]

200 very similar, main difference in instruction to top of reservoir Scored 2011 LC W/79K OMG CLEAN (2012 missing link)
I've one on 100 series somewhere!

 

[MH_Stevens]

REPLY TO 2001LC

Wheel bearings good
Disks and pads etc look good
Fluid drawdown about 28 seconds looks good

BUT I see I did a BAD bleed job and will repeat using a valve assist
AND the driver side rear brake, the one where I reported no fluid flow without assist, is getting hot.

 

[2001LC]

28 second is out of spec. Book FSM doesn't say what that means and I've never seen. Try timing again after bleed and ABS activation.

Come back here and report or PM me if you don't get 30 to 40 seconds. If you use @ in front of 2001 works better.

Brakes must be understood and done right.

 

[MH_Stevens]

OK now have flushed brake fluid, activated ABS a few times and correctly bleed system. Pump now runs for about 32 seconds.
Still getting the pulsing on braking so maybe it is the fairly new rotors have warped? But warped rotors would cause symptoms all the time no? And this is not always so but much worse when b raking going down hill.

 

[2001LC]

No, sometimes they do it when hot. Have them machine turned.

 

[nissanh]

Did you install oem rotors or aftermarket?
I did my brakes with oem rotors and pads and bled the system ln all 4 coners like an ordinary car with the exception of key on engine off. The result is a success!

Aftermarket rotots are poorly made and will fail. The metal used in the rotor has to have specific expansion coefficient

 

[MH_Stevens]

I have to adit I used NAPA rotors. Any hints on where to get OEM rotors. Being so heavy shipping might be a problem. Anyone know a discount dealer in Southern cal?

 

[MH_Stevens]

UPDATE. So I got OEM rotors, $67 at Olanthe, Kansas dealership but with shipping not much better than list local. But I notice grease leaking from the front wheel drive shafts, see pictures. There is a bit of looseness in the drive shafts but steering arm is tight. Might this be a related issue?

 

[2001LC]

That is just a little CV grease weeping from under boot at clamp. Clean to make sure it's not a torn boot. Then re clamp, if not torn boot.

FSM inspection for FDS CV's: Hold the center axle, the turn/twisting tulip (CV bearing housing). If remarkable play felt, replace FDS. .

Also inspect outer axle splines (teeth) and snap ring groove. If worn replace FDS

 

[MH_Stevens]

Problem solved. I may have wasted $200 on OEM rotors as what I took of checked out as good. Re-packed front bearings so I suspect they were too loose.
Thanks for all the input.
Morale I should have re-done bearings first but there was never any movement in wheel that could be made by hand.

 

[2001LC]

I find grabbing tire while raised off the ground, t the 12 & 6 o'clock positions. Is helpful to determine if wheel bearings loose. But ball joints could also be bad, which tire/wheel movement/play may show at 12 & 6 also. Or bearings may only be a little loose. So a second test, is to put a finger between brake caliper and wheel. I then pushed and pulled on tire/wheel. If finger is pinched while between the two points, bearing are loose.

 

[MH_Stevens]

that's good to know. I'll give it a try